Quaternary ammonium salts of esters of salicylic acid as rust inhibitors



United States Patent 3,433,607 QUATERNARY AMMONIUM SALTS 0F ESTERS 0FSALICYLIC AClD AS RUST INHIBITORS Elizabeth L. Fareri, Pittsburgh,Robert J. McGuire, Monroeville, and Harold 0. Strange, Penn HillsTownship, Allegheny County, Pa., assignors to Gulf Research &Development (Iompauy, Pittsburgh, Pa., a corporation of Delaware NoDrawing. Filed Aug. 2, 1965, Ser. No. 476,717 US. CI. 44-63 8 ClaimsInt. Cl. C101 1/22 ABSTRACT OF THE DISCLOSURE Quaternary ammonium saltsof esters of salicyclic acid are used as rust inhibitors in hydrocarbonoil.

This invention relates to chemical compounds and to compositionscontaining said compounds.

The chemical compounds of this invention are quaternary ammonium saltsof esters of salicylic acid. These compounds have been found to exhibithigh activity as rust inhibitors when present in a minor concentrationin a hydrocarbon oil, such as fuel oil. The compounds of this inventionare particularly effective rust inhibitors when present in a hydrocarbonoil which is in contact with a water phase or is otherwise in acondition conducive to rust formation.

The quaternary ammonium salts of esters of salicylic acid of thisinvention can be selected from compounds having the general structurewherein R is a normal or iso alkyl, normal or iso alkenyl, aralkyl orcycloalkyl substituent containing 1 to 22 carbon atoms and can besubstituted with substituents such as nitrogen, phosphorus, sulfur oroxygen.

R may be absent or is a normal or iso alkyl, normal or iso alkenyl,aralkyl or cycloalkyl substituent containing 1 to 22 carbon atoms andcan be substituted with substituents such as nitrogen, phosphorus,sulfur or oxygen.

R R R and R are each a normal or iso alkyl, normal or iso alkenyl,aralkyl or cycloalkyl substituent containing l to 22 carbon atoms whichcan be substituted with substituents such as oxygen, nitrogen,phosphorus, or sulfur, at least one of said groups containing at leastfour carbon atoms,

N is nitrogen and can be the nitrogen of a heterocyclicnitrogen-containing ring such as imidazoline, pyridine, thiazine orpiperazine, in which case R and R are members of the heterocyclic ringand at least one of the substituents R and R contains at least fourcarbon atoms, C is carbon, and O is oxygen.

Although R,,, R R and R, generically encompass oxygen-containingsubstituents, compounds wherein R,,, R R and R are hydrocarbonsubstituents which are free of hydroxyl groups with or without an etherpolymer thereof unexpectedly possess different utility from compoundswherein R R R and R have a hydroxyl group with or without an etherpolymer thereof, and the latter group of compounds is coveredspecifically in application Ser. No. 476,666, filed on the same date asthis application by Elizabeth L. Fareri, Robert J. McGuire and EdwardMitchell.

Preferred compounds of this invention include quaternary ammonium saltsof octyl, dodecyl, tridecyl or hexadecyl salicylates where thequaternary ammonium group is selected from the following:

Alkyltrimethylammonium wherein the alkyl group is a C to C -substituent;dialkyldimethylammonium wherein the alkyl groups are C,,- to C-substituent; or mixtures of said monoalkyltrimethylammonium and saiddialkyldimethylammonium groups.

Some commercial starting materials which can be utilized as thequaternary ammonium base are Arquad C, Arquad S, Arquad T, Arquad 12,Arquad 18, Arquad 2C, Arquad 2S, Arquad 2HT, Arquad T-2C, and ArquadS-2C, all of which are commercial products. Arquad C, Arquad S, ArquadT, Arquad l2, and Arquad 18 are alkyltrimethylamrnonium chlorideswherein the symbols C, S, and T indicate that the alkyl substituentcomes from coco, soya bean oils or fats, or tallow, respectively, whilein Arquad 12 and Arquad 18 the alkyl substituent is essentially puredodecyl or octadecyl, respectively. Arquad 2C, Arquad 2S and Arquad 2HTare dialkyldimethylammonium chlorides wherein the alkyl substituent iscoco, soya and hydrogenated tallow, respectively, and Arquad T-2C andArquad S-2C are mixtures of the indicated alkyltrimethylammoniumchlorides and dialkyldimethylammonium chlorides.

Salicylic acid is a convenient starting material in the preparation ofthe quaternary ammonium salicylates of this invention. Salicylic acidcontains a hydroxyl radical and a carboxylic acid radical at orthopositions on a benzene ring. In preparing the quaternary ammonium saltsof this invention, the reactant containing the quaternary ammoniumcation is reacted with the hydroxyl radical of the salicyclic acidrather than with the carboxylic radial so that the salt formed is aquaternary ammonium phenate rather than a quaternary ammoniumcarboxylate. However, the carboxylic acid radical is considerably moreacidic and therefore more reactive with the quaternary ammonium cationthan is the hydroxyl radical and in order for the quaternary ammoniumcation to react with the hydroxyl radical rather than with thecarboxylic acid radical the salicylic acid must be esterified prior tothe reaction thereof with the quaternary ammonium compound. Therefore,the preparation of the quaternary ammonium salt of this invention is atwo-step process in which the order of performance of the steps iscritical, i.e., the salicylic acid starting material is first esterifiedby reaction with an alcohol and only after esterification is itconverted to a quaternary salt.

In the following specific example for the preparation of the compoundsof this invention from salicylic acid, the more reactive carboxylic acidradical is first reacted with an alcohol to form an ester. Thereupon, acommercial quaternary ammonium chloride is converted to thecorresponding quaternary ammonium hydroxide. The quaternary ammoniumhydroxide is then reacted with the hydroxyl radical of the ester ofsalicylic acid to form a quaternary ammonium salt of salicylic acidester.

EXAMPLE Step 1.Preparation of isooctyl salicylate from salicylic acid Amixture containing 900 grams of salicylic acid, 1300 grams (10 moles) ofisooctyl alcohol, 30 grams of p-toluenesulfonic acid and 1000milliliters of toluene was heated at reflux in a 5-liter flask fittedwith a Dean and Stark trap. Reflux was continued until no more watercollected in the trap. The solution was cooled to room temperature andextracted with one liter of water, then with one liter of 10 percentsodium bicarbonate solution followed by a washing with one liter ofwater. The extracted solution was dried over anhydrous sodium sulfate,filtered and vacuum-distilled. After distillation of toluene and excessisooctyl alcohol, 1568 grams of a clear oil was collected at l50-l60 C.and 3.2 millimeters pressure. Analysis of the product showed 72.21percent carbon, 8.90 percent hydrogen, 18.21 percent oxygen and amolecular weight of 265. Theoretically, isooctyl salicylate contains71.9 percent carbon, 8.8 percent hydrogen, and 19.2 percent oxygen, andhas a molecular weight of 250.

Step 2.-Preparation of di(hydrogenated tallow)dimethylammonium isooctylsalicylate from isooctyl salicylate Ninety grams (0.154 mole) ofdi(hydrogenated tallow)dimethylammonium chloride as a 75 weight percentpaste containing isopropanol and a small amount of water, was dissolvedin 200 milliliters of benzene. The composition of the 75 weight percentof the paste which consisted of di(hydrogenated tallow)dimethylammoniumchloride was 75 percent by weight distearyldimethylammonium chloride, 1percent by weight dioctadecenyldimethylammonium chloride, and 24 percentby weight dihexadecyldimethylammonium chloride. With stirring, a warmsolution containing 10.1 grams (0.153 mole) of potassium hydroxide(assay 85%) in absolute ethanol was added to the benzene solution. Theprecipitated potassium chloride was removed by filtration. To thefiltrate was added 38.4 grams (0.153 mole) of isooctyl salicylate.Solvent was removed. The product, a brown oil which solidified oncooling, contained 1.81 percent of nitrogen. The calculated nitrogencontent of di(hydrogenerated tallow)dimethylammonium octyl salicylate is1.75 percent.

Tests were conducted to illustrate the high rust arresting effectivenessof the compounds of this invention as compared to a control fuel oilsample without additives and as compared to a control fuel oil samplecontaining calcium octyl salicylate. In conducting these tests, a testsolution was prepared by placing a mixture of 80 percent by volume offuel oil or fuel oil plus additive with 20 percent by volume ofdistilled water into a 4-ounce jar and shaking vigorously for oneminute. A clean specimen of SAE 1020 steel was immersed nearlyvertically into each test jar and the jar was stored at roomtemperature. The steel specimens were inspected and rated after 1 day, 3days and 7 days, respectively, and the results of the inspection areshown in the following table. A rating of signifies no rust; 1 signifies1 to percent of the surface area rusted; 2 signifies 6 to 25 percent ofthe surface area rusted; 3 signifies 26 and 50 percent of the surfacearea rusted; and 4 signifies greater than 50 percent of the surface arearusted. The results of the tests are presented in the following table,

1 day 3 days 7 days Sample Fuel Water Fuel Water Fuel Water oil layeroil layer 011 layer layer layer layer Fuel oil control 2 0 4 0 4 0 4Fuel oil control plus calciuin iso octyl d salicy ate, 30 poun s per1,000 barrels..." 0 4 0 4 0 4 Fuel oil control plus di(hydrogenatedtallow) dirnethyl ammolnium isooctydl salicy ate, 20 poun 5 per 1,000barrels 0 1 0 1 0 1 1 Heavy red and black corrosion where water dropletscling to or creep over portion of steel specimen in the fuel 011 phase.

2 Typical fuel oil inspections:

Gravity: API, AS'IM D287 End Point. 632 At 10 F 434 At 50 F 502 At F.590 Residue 1.0

It is seen from the above table that in the test with the fuel oilcontrol sample without additives and in the test with the fuel oilcontrol sample plus calcium isooctyl salicylate there was rusting overmore than 50 percent of the surface area of the steel specimen in thewater phase and also heavy corrosion in the steel specimen in the fueloil phase where water droplets clung to or crept over the portion of thespecimen in the fuel oil phase. In contrast, the table shows that in thetest with the fuel oil sample plus di(hydrogenatedtallow)dirnethylammonium isooctyl salicylate there was rusting over only1 to 5 percent of the surface area of the steel specimen in the waterphase, while there was no rust in the portion of the steel specimen inthe fuel oil phase.

The quaternary ammonium salicylates of this invention are oil solubleand can be present in hydrocarbon oils over a wide range ofconcentrations. For example, they can be generally present inhydrocarbon oils over a concentration range of about 0.002 up to about10 percent by Weight, the higher region of the range being especiallyuseful when preparing a concentrate, or, preferably, over aconcentration range of about 0.005 to about 0.1 percent by weight.Although useful in a wide variety of hydrocarbon oils such as gasoline,jet fuels, diesel fuels, etc., the quaternary ammonium salicylates ofthis invention are especially useful in fuel oils, such as blends ofstraight run and catalytically cracked fuel oils. Also, the compounds ofthis invention are primarily useful for rust inhibition in oils whichare in contact with an aqueous phase.

Various changes and modifications can be made without departing from thespirit of this invention or the scope thereof as defined in thefollowing claims.

We claim:

1. A composition comprising a hydrocarbon oil in contact with waterhaving dissolved in said oil an oil soluble quaternary ammonium salt ofan ester of salicylic acid, said salt being a quaternary ammoniumphenate with the ester portion thereof formed from an alcohol containing1 to 22 carbon atoms.

2. The composition of claim 1 wherein there is attached to the ringstructure of said salicylic acid in alkyl, alkenyl, aralkyl orcycloalkyl substituent containing 1 to 22 carbon atoms.

3. The composition of claim 1 wherein attached to the quaternarynitrogen atom are four hydroxyl-free substituents selected from thegroup consisting of alkyl, alkenyl, aralkyl, and cycloalkyl substituentscontaining 1 to 22 carbon atoms, at least one of said substituentscontaining at least 4 carbon atoms.

4. The composition of claim 1 wherein said hydrocarbon oil is fuel oil.

5. The composition of claim 1 wherein the concentration of saidquaternary ammonium salt of an ester of salicylic acid in saidhydrocarbon oil is between about 0.002 and percent by weight.

6. A composition comprising a hydrocarbon oil in contact with waterhaving dissolved in said oil a compound having the structure.

wherein R is a substituent containing 1 to 22 carbon atoms, R and R areeach substituents containing 1 to 22 carbon atoms, at least one of whichcontains at least 4 carbon atoms, and R and R are members of the sameheterocyclic ring containing the quaternary nitrogen atom.

8. A composition comprising a hydrocarbon oil in contact with waterhaving dissolved in said oil about 0.002 to 10 percent by weight of acompound having the structure wherein R is an alkyl, alkenyl, aralkyl orcycloalkyl substituent containing 1 to 22 carbon atoms, R R R and R areeach hydroXyl-free alkyl, alkenyl, aralkyl or cycloalkyl substituentscontaining 1 to 22 carbon atoms,'at least one of which contains at least4 carbon atoms, and R is an alkyl, alkenyl, aralkyl or cycloalkylsu-bstituent containing 1 to 22 carbon atoms.

References Cited UNITED STATES PATENTS 2,629,649 2/ 1953 Wachter et a1.252-392 2,679,500 5/1954 Gash et a1 260-243 2,739,871 4/ 1956 Senkus252-392 2,745,809 5/1956 Cardwell et al. 252-392 2,831,019 4/ 1958Erskine 252-392 2,861,874 11/1958 OKelly et a1. 44-66 2,920,040 1/ 1960Jolly 252-392 DANIEL E. WYMAN, Primav'y Examiner.

Y. H. SMITH, Assistant Examiner.

US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,433,607 March 18, 1969 Elizabeth L. Fareri et a1.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as shown below: Column 2,line 49, "radial" should read radical Column 6, lines 4 to ll, theportion of the formula reading:

\ -N should read --N+-- signed and sealed this 31st day of March 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

